Front electrode for use in photovoltaic device and method of making same

Abstract

This invention relates to a front electrode/contact for use in an electronic device such as a photovoltaic device. In certain example embodiments, the front electrode of a photovoltaic device or the like includes a multilayer coating including at least one transparent conductive oxide (TCO) layer (e.g., of or including a material such as tin oxide, zinc oxide, or the like) and at least one conductive substantially metallic IR reflecting layer (e.g., based on silver, gold, or the like). In certain example instances, the multilayer front electrode coating may include a plurality of TCO layers and/or a plurality of conductive substantially metallic IR reflecting layers arranged in an alternating manner in order to provide for reduced visible light reflection, increased conductivity, and/or increased infrared (IR) reflection capability.

1 . A photovoltaic device comprising:
 a front glass substrate;   an active semiconductor film;   an electrically conductive and substantially transparent front electrode located between at least the front glass substrate and the semiconductor film;   wherein the substantially transparent front electrode comprises, moving away from the front glass substrate toward the semiconductor film, at least a first substantially transparent conductive substantially metallic infrared (IR) reflecting layer comprising silver and/or gold, and a first transparent conductive oxide (TCO) film located between at least the IR reflecting layer and the semiconductor film.   
   
   
       2 . The photovoltaic device of  claim 1 , wherein the first TCO film comprises one or more of zinc oxide, zinc aluminum oxide, tin oxide, indium-tin-oxide, and indium zinc oxide. 
   
   
       3 . The photovoltaic device of  claim 1 , wherein the substantially transparent front electrode further comprises a second substantially transparent conductive substantially metallic infrared (IR) reflecting layer comprising silver and/or gold, and wherein the first transparent conductive oxide (TCO) film is located between at least said first and second IR reflecting layers. 
   
   
       4 . The photovoltaic device of  claim 3 , wherein the first and second IR reflecting layers each comprise silver. 
   
   
       5 . The photovoltaic device of  claim 3 , wherein the front electrode further comprises a second TCO film which is provided between at least the second IR reflecting layer and the semiconductor film. 
   
   
       6 . The photovoltaic device of  claim 1 , further comprising a dielectric layer having a refractive index of from about 1.6 to 2.0 located between the front glass substrate and the front electrode. 
   
   
       7 . The photovoltaic device of  claim 1 , further comprising a dielectric layer having a refractive index of from about 1.6 to 2.2 located between the front glass substrate and the front electrode. 
   
   
       8 . The photovoltaic device of  claim 6 , wherein the dielectric layer comprises silicon oxynitride and/or an oxide of titanium. 
   
   
       9 . The photovoltaic device of  claim 1 , further comprising a back electrode, wherein the active semiconductor film is provided between at least the front electrode and the back electrode. 
   
   
       10 . The photovoltaic device of  claim 1 , wherein the first IR reflecting layer is from about 3 to 12 nm thick, and the first TCO film is from about 40 to 130 nm thick. 
   
   
       11 . The photovoltaic device of  claim 1 , wherein the front glass substrate and the front electrode taken together have a transmission of at least about 80% in at least a substantial part of a wavelength range of from about 450-600 nm. 
   
   
       12 . The photovoltaic device of  claim 1 , wherein the front glass substrate and front electrode taken together have an IR reflectance of at least about 45% in at least a substantial part of an IR wavelength range of from about 1400-2300 nm. 
   
   
       13 . The photovoltaic device of  claim 1 , wherein the front glass substrate and front electrode taken together have an IR reflectance of at least about 45% in at least a majority of an IR wavelength range of from about 1000-2500 nm. 
   
   
       14 . An electrode adapted for use in a photovoltaic device including a semiconductor film, the electrode comprising:
 an electrically conductive and substantially transparent multilayer electrode supported by a glass substrate;   wherein the substantially transparent multilayer electrode comprises, moving away from the glass substrate, at least a first substantially transparent conductive substantially metallic infrared (IR) reflecting layer comprising silver and/or gold, and a first transparent conductive oxide (TCO) film.   
   
   
       15 . The electrode of  claim 14 , wherein the first TCO film comprises one or more of zinc oxide, zinc aluminum oxide, tin oxide, indium-tin-oxide, and indium zinc oxide. 
   
   
       16 . The electrode of  claim 14 , wherein the substantially transparent electrode further comprises a second substantially transparent conductive substantially metallic infrared (IR) reflecting layer comprising silver and/or gold, and wherein the first transparent conductive oxide (TCO) film is located between at least said first and second IR reflecting layers. 
   
   
       17 . The electrode of  claim 16 , wherein the first and second IR reflecting layers each comprise silver. 
   
   
       18 . The electrode of  claim 16 , wherein the electrode further comprises a second TCO film, positioned so that each of the first and second IR reflecting layers are located between the glass substrate and the second TCO film. 
   
   
       19 . The electrode of  claim 14 , further comprising a dielectric layer having a refractive index of from about 1.6 to 2.5 located between the glass substrate and the first IR reflecting layer. 
   
   
       20 . The electrode of  claim 14 , wherein the first IR reflecting layer is from about 3 to 12 nm thick, and at least the first TCO film is from about 40 to 130 nm thick. 
   
   
       21 . The electrode of  claim 14 , wherein the glass substrate and the electrode taken together have a transmission of at least about 80% in at least a substantial part of a wavelength range of from about 450-600 nm and/or 450-700 nm. 
   
   
       22 . The electrode of  claim 14 , wherein the glass substrate and the electrode taken together have an IR reflectance of at least about 45% in at least a substantial part of an IR wavelength range of from about 1000-2500 nm. 
   
   
       23 . The electrode of  claim 14 , wherein the glass substrate and the electrode taken together have an IR reflectance of at least about 55% in at least a majority of an IR wavelength range of from about 1000-2500 nm. 
   
   
       24 . The electrode of  claim 14 , wherein the glass substrate and the electrode taken together have an IR reflectance of at least about 45% in at least a substantial part of an IR wavelength range of from about 1400-2300 nm. 
   
   
       25 . The electrode of  claim 14 , wherein the electrode is adapted to be used as a front electrode in the photovoltaic device.